Sanitary napkin whose rear portion includes a longitudinally extending ridge

ABSTRACT

The present invention relates to an absorbent article in the form of a sanitary napkin, a panty liner or an incontinence protector and comprising a front portion, a rear portion, a liquid-permeable top sheet ( 2 ), a liquid-impermeable backing sheet ( 3 ), and an absorbent body ( 1 ) enclosed between the top and backing sheets, wherein the rear portion of the article includes a longitudinally extending ridge-shaped elevation ( 9 ) that projects out from that side of the article that contains the top sheet. According to the invention a central string of material ( 8 ) extends in the rear portion of the article and the absorbent body ( 1 ) between the top sheet ( 2 ) and the backing sheet ( 3 ) in the rear portion of the article extends around the long sides of said string. The invention also relates to a method of manufacturing such an article.

FIELD OF INVENTION

The present invention relates to an absorbent article in the form of asanitary napkin, a panty liner or an incontinence protector that has afront and a rear portion and which includes a liquid-permeable topsheet, a liquid-impermeable backing sheet, and an absorbent bodyenclosed between said top sheet and backing sheet, wherein the rearportion of the article has a longitudinally extending projecting partthat projects out in the form of a ridge from that side of the articlewhich includes the top sheet. The invention also relates to a method ofmanufacturing such an article.

BACKGROUND OF THE INVENTION

Sanitary napkins whose rear portions include ridge-like elevated partsare known to the art, for instance from U.S. Pat. No. 4,673,403, U.S.Pat. No. 4,804,380 and U.S. Pat. No. 4,846,824. The raised ridge-likeparts are well adapted to the female anatomy and therewith reduce therisk of menstruation fluid running along the upper side of the napkin tothe edges thereof and therewith soiling the undergarments of the wearer.The ridge-like parts also prevent fluid/liquid running backwards whenthe wearer lies on her back. When wearing such a napkin, the ridge-likepart extends between the buttocks of the wearer, therewith causing thenapkin to be held safely in position and preventing the napkin fromslipping to one side in use. In the case of the known napkins, theridge-like raised part is either obtained by bending the absorbent bodyinto a longitudinally extending fold and then fastening together thoseparts of the backing sheet that abut one another in the fold in one ormore places, or by including a profiled insert in the absorbent body.When folding the absorbent body in accordance with the first-mentionedmethod, the absorbent body is liable to break or be thinned out alongthe fold, therewith impairing the liquid transport properties of thebody. The inclusion of an insert complicates the manufacture of thenapkin.

The present invention aims to provide an absorbent article of theaforesaid kind in which the ridge-like part curves gently and has beenproduced without including an insert in the absorbent body.

SUMMARY OF THE INVENTION

These objects are achieved in accordance with the invention with anabsorbent article in the form of a sanitary napkin, a panty liner or anincontinence protector which includes a front portion, a rear portion, aliquid-permeable top sheet, a liquid-impermeable backing sheet, and anabsorbent body or pad enclosed between the top sheet and backing sheet,and article having in it rear portion a longitudinally outstanding partwhich extends in the form of a ridge from that side of the article thatincludes the top sheet, said article being characterised in that acentral string of material extends in the rear portion of the article,and in that the absorbent body enclosed between the top and backingsheets extends around the long sides of said string in the rear portionof the article. Folding of the absorbent body around a string ofmaterial results in a gently rounded ridge-like elevation.

In one preferred embodiment of the invention, the string comprises arear portion of a longitudinally extending strip of flexible materialthat presents a high coefficient of friction to textile material andwhich extends in the front and the rear portions of the article and isattached to the backing sheet on that side thereof distal from theabsorbent body. This ensures that the front portion of the article willnot move relative to the undergarments of the wearer then the article isin use.

Those parts of the article which extend around the long sides of thestring of tape material extending in the rear portion of the articleabut with and are attached to each other in an least one place. Thestrip of flexible material is preferably comprised of an elastic foammaterial which is mounted in a stretched state in the rear portion ofthe article and in a relaxed state in the front portion of said article,wherewith mutually adjacent parts of the string of strip material arefastened together in at least one place. The strip extends symmetricallyon both sides of the longitudinal symmetry axis of the article and hasin the front portion of said article a width which is greater than halfthe smallest width of the article in its front portion.

The present invention also relates to a method of manufacturing anabsorbent article which comprises a front portion and a rear portionthat includes a longitudinally extending elevated portion, said methodcomprising the steps of:

-   (a) placing a body of absorbent material on a first sheet of    liquid-permeable material;-   (b) placing a second sheet comprised of liquid-impermeable material    on the body of absorbent material and joining the first and the    second sheets together at those parts thereof that lie outside the    body of absorbent material, therewith forming a generally flat    composite body,    characterised by the further steps of-   (c) placing a strip of flexible material on the second sheet of said    composite body and causing said strip to extend over at least a part    of a front and a rear portion of the composite body;-   (d) fastening the strip to said second sheet in the front portion of    the composite body;-   (e) forming a longitudinally extending string from that part of the    strip which extends in the rear portion of the composite body; and-   (f) folding those parts of the composite body lying on respective    sides of the longitudinal string inwardly around said string and    fastening said body parts together in at least one place.

In a preferred embodiment of the invention, said strip is comprised ofelastic material and the part of the strip that extends in the rearportion of the composite body is stretched prior to carrying out step(f). The longitudinally extending string is formed by folding or rollingthe strip together and fastening those parts of the composite bodyfolded in on respective sides of the longitudinal string of stripmaterial to said string in at least two sections which are mutuallyspaced apart in the longitudinal direction and which extend around thecircumference of the string. In one variant, the part of the strip thatextends in the rear portion of the composite body is formed into alongitudinally extending string before the strip is placed on thecomposite body.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanyingdrawings, in which

FIG. 1 is a schematic perspective plan view of a sanitary napkinaccording to one embodiment of the invention;

FIG. 2 is a schematic perspective illustration of the sanitary napkin inFIG. 1 taken from beneath;

FIG. 3 is a cross-sectional view taken on the line III—III in FIG. 1;

FIGS. 4A, B-7A, B illustrate schematically different steps in themanufacture of an inventive sanitary napkin;

FIG. 8 illustrates schematically a method of folding a rear portion of afriction-enhancing layer fastened to the napkin of FIGS. 4–7;

FIG. 9 is a schematic illustration of a production line for themanufacture of an inventive sanitary napkin;

FIG. 10 illustrates schematically part of the arrangement shown in FIG.9; and

FIG. 11 illustrates schematically a further method of manufacturing aninventive sanitary napkin.

DESCRIPTION OF EMBODIMENTS

FIGS. 1–3 illustrate a sanitary napkin according to a preferredembodiment of the invention. The napkin includes conventionally anabsorbent body or pad 1 enclosed between two casing sheets, i.e. a topsheet 2 and a backing sheet 3. The top sheet and the backing sheet arejoined together, e.g. glued or heat-welded, in those sheet parts thatexternally surround the absorbent body. The napkin also includes onrespective sides of its longitudinal symmetry line two compression lines4, 5 that extend along a major part of the length of the napkin andequidistantly from respective long edges thereof.

The top sheet 2 is comprised of a liquid-permeable material, preferablynonwoven material although other materials may be used, such asperforated plastic film, for instance a thermoplastic material such aspolyethylene. The nonwoven sheet may consist of natural fibres, such ascellulose or cotton fibres, or may consist of synthetic fibres, such aspolyethylene, polypropylene, polyester, polyurethane, nylon orregenerated cellulose fibres. Alternatively, the top sheet may comprisea lamination. The material in the top sheet is preferably hydrophobic orhas been treated so as to obtain a hydrophobic surface. It will beunderstood that the invention is not restricted to the use of saidmaterials and that all materials that are used as top sheet material inabsorbent articles may be used in the top sheet 2.

The backing sheet 3 is comprised of a liquid-impermeable material,preferably plastic film produced from polyethylene, polypropylene orpolyester. The backing sheet may also conveniently be microporous, i.e.will allow air and vapour to pass through but not liquid. The backingsheet may alternatively consist of a liquid-permeable material that hasbeen coated with plastic, resin or some other liquid-imperviousmaterial. The backing sheet may be given a textile-like feeling, byforming said sheet from a lamination of nonwoven and liquid-imperviousmaterial, said nonwoven sheet being faced outwards. All materials usedin the backing sheets of absorbent articles can be used in the presentcontext.

The absorbent body 1 is preferably comprised of cellulose fluff,although other materials used for absorbent bodies in absorbent articlescan be used in an absorbent body according to the invention. Theabsorbent body may comprise one or more layers of absorbent material,wherewith so-called superabsorbent material can be mixed in one or moreof the layers, and it is also conceivable to form the whole of thelowermost layer in a multilayer absorbent body from superabsorbentmaterial, i.e. the layer that lies proximal to the backing sheet. Theabsorbent body 1 of the illustrated embodiment comprises a single sheetof cellulose pulp that has been compressed to a density of 0.1–0.2g/cm³. The cellulose pulp may exist in the form of rolls, bales orsheets that are dry-defibred and converted in a fluffed state to a pulpmat, sometimes while mixing-in so-called superabsorbents, i.e. polymersthat are able to absorb liquid in an amount corresponding to severaltimes their own weight. Other materials that can be used are differenttypes of natural fibres, such as cotton fibres, peat fibres or the like.Synthetic absorbent fibres may also be included in the absorbent body.

According to the invention, a strip 6 of flexible material that has ahigh coefficient of friction with respect to textile material isfastened to the underside of the napkin, e.g. glued thereto. That partof the strip extending in the front portion 7 of the napkin is open toits full width, whereas the rear portion of the strip 6 is folded orrolled together to form a string 8 that extends along the longitudinalsymmetry line A—A of the napkin. The rear portion of the napkin isfolded around the string 8 and fastened thereto, e.g. glued. Thisresults in a ridge-like elevation 9 on the upper side of the napkin,i.e. the side that is intended to lie in contact with the wearer's body.In the illustrated embodiment, the rear portion of the napkin is foldedaround the full periphery of the string 8 along a string section and thefolded parts of the napkin are fastened together along this section,i.e. by gluing or welding, as will be seen from FIGS. 2 and 3.

When donning the illustrated napkin, the napkin is positioned so thatthe ridge-like elevation 9 will partially extend between the wearer'sbuttocks. This provides good protection against rearward leakage. Theridge-like elevation 9 conforms effectively to the female anatomy inother respects and therewith contributes in greatly reducing the risk ofliquid running along the upper surface of the napkin and out to theedges thereof. The ridge-like elevation 9 also prevents the napkin frommoving sideways as the wearer moves. When the napkin is worm, the frontportion 7 of the strip 6 lies against the wearer's undergarments andprevents the front portion of the napkin moving relative to saidgarments as a result of frictional forces. A sanitary napkin constructedin this manner does not therefore require the provision of an adhesivelayer on the backing sheet in order to fasten the napkin to theundergarments of the wearer, since the napkin is held securely in placeby the ridge 9 and the friction strip 6.

Because the ridge-like elevation is formed by folding the absorbent body1 and its casing sheets 2, 3 around the string 8, the ridge 9 obtains agently curved cross-sectional shape. The width of the ridge can bevaried in many ways, for instance by varying the width of the rearportion of the strip 6 or by varying that part of the periphery of thestring 8 that is embraced by the absorbent body 1. As will be seen fromFIGS. 1 and 2, the ridge 9 is broader in those sections in which thebacking sheet 3 is not fastened to the string 8 around the whole of itscircumference.

In the illustrated embodiment, the strip 6 is produced from an elasticplastic foam material, preferably foamed polyethylene that has opencells, although other foam materials may be used, such as viscous foam,polyacrylate foam, polyester foam or polystyrene foam having open cellstructures. It is preferred to stretch the string 8 before the rearportion of the napkin is folded around the string, and to keep thestring stretched as the portion of the napkin folded around said stringis fastened thereto. The elastic string tends to return to itspre-stretched state and will therefore contract when the load on thefinished napkin is removed. The ridge 9 will therewith obtain a somewhatcurved shape in its longitudinal direction, this curvature depending onthe extent to which the string 8 is stretched prior to attaching therear portion of the napkin thereto. The cross-sectional area of thestring will decrease somewhat as the string 8 is stretched.

One embodiment of a method of manufacturing a sanitary napkin inaccordance with the invention will now be described with reference toFIGS. 4–8.

The sanitary napkin is preferably manufactured continuously, by placinga row or line of absorbent bodies on a travelling first web of material.A second web of material is then placed on top of the absorbent bodiesso as to form a composite web consisting of two casing sheets andintermediate absorbent bodies. Individual napkins, which are still notprovided with friction strips, are then cut from the composite web.

FIGS. 4A, B-7A, B illustrate the various steps in the final stages ofthe method of providing a sanitary napkin with a ridge-like elevation,as seen in plan view with the backing sheet facing towards the viewerand in side view seen from the rear short side of the napkinrespectively. Those components of the napkin shown in FIGS. 4A, B-7A, Bthat find correspondence in components shown in FIGS. 1–3 have beenidentified with the same reference signs to which a prime has beenadded.

In a first step (FIGS. 4A; B), a strip 6 of foam material is placed onthe backing layer 3′ of the napkin cut from said composite web and thestrip 6′ is fastened to the backing sheet 3′ in the front portion of thenapkin, within the distance reference a in FIG. 4A. The strip ispreferably glued to said sheet, although it may also be welded thereto,e.g. spot-welded. The strip is not fastened to the backing sheet in therear portion of the napkin within the distance identified by reference bin FIG. 4A.

In the second step of the final stage (FIGS. 5A, B, 6A, B) the strip 6′is stretched in the rear portion of the napkin and its side-edges foldedin towards each other.

The resultant string 8′ is then folded into an inverse S-shape, as shownschematically in FIG. 8 and is compressed so that the folded parts ofsaid string 8′ will lie in abutment with one another.

Finally (FIGS. 7A, B), the absorbent body 1′ in the rear portion of thenapkin is folded around the string 8′ and fastened thereto. Theabsorbent body is folded around the full circumference of the string 8′within one section thereof, and those parts of the backing sheet 3′which are therewith brought into mutual abutment are fastened togetherin this string section. The string will therewith be fully embraced bythe absorbent body within said string section, thereby preventing thestring 8′ of elastic material from changing its shape in said stringsection as a result of its inherent spring forces.

As will be understood, it is not necessary for the rear portion of thenapkin to include a section in which the string 8′ is fully embraced bythe absorbent body and that the string 8′ can be prevented fromdeparting from its compressed state, by virtue of its intrinsic springforce, and from taking a more extended state, by fastening thecompressed parts of the string 8′ together locally, e.g. at thebeginning of the string and at its free end or in an intermediateportion of said ends. However, it is preferred to sustain the string ina compressed state with the aid of absorbent body sections folded aroundsaid string, since this obviates the need of applying glue to the stringand therewith significantly facilitates manufacture of the napkin.

FIG. 9 is a schematic illustration of an inventive napkin productionline.

A web 10 of top sheet material, e.g. nonwoven material, is unwound froma storage reel 11 and transported on a transporter (not shown), e.g. avacuum transporter, to the right in FIG. 10, as indicated with an arrow.A device 12 for laying a row of line of absorbent bodies 13 on the web10 is positioned downstream of the reel 11. Downstream of the device 12is a second storage reel 14 from which a second web 15 comprisingbacking material is unwound and placed on the line of absorbent bodies13. The composite web consisting of the two webs 10, 15 and theabsorbent bodies 13 is then passed through a device 16 locateddownstream of the device 14 and functioning to fasten the webs 10, 15together at parts which lie externally of the bodies 13. The webs 10, 15are preferably glued together, wherewith the glue is convenientlyapplied to the web 15 immediately said web is placed over the absorbentbodies 13. The webs may alternatively be welded together, e.g. byultrasound welding. The composite web then passes through a cutting orpunching device 17 in which individual absorbent articles 18 are cut orpunched from the composite web. The components described hitherto aretypical in production lines for sanitary napkins and like articles, asare also other components, for instance such as further devices forlaying bodies on top of the absorbent bodies 13 to form multilayerabsorbent bodies, or means for providing the napkin with compressionlines or elastic elements, all of which may be included in theproduction line.

Located downstream of the punch 17 is a device 19 for applying andfastening a strip of plastic foam material 20 to the backing sheet 15 ofeach article 18 cut from the composite web. The articles 18 and astrip-forming web of material 20 taken from a storage reel (not shown)are passed through the nip of a pair of rolls 21, 22 in the device 19.Prior to entering the roll nip, the web 20 is provided intermittentlywith a glue layer on parts of the side facing towards the article 18,with the aid of an intermittently operating glue applicator 23. The web20 and the articles 18 fastened thereon are then passed to a transferwheel 24 which has a higher peripheral speed than the roll 22. Thoseparts of the web 22 on which no articles 18 are fastened will thereby bestretched and the spacing between the articles 18 therewith increased.Located downstream of the transfer wheel 24 is a device 25 in whichthose sections of the web in which no articles 18 are fastened arefolded together in the manner shown in FIGS. 4A–6B and FIG. 8, so as toform a string. The web 20 and appendant articles 18 then pass through adevice 26 in which parts of the articles 18 are folded-in around theformed string and fastened thereto in the manner shown in FIGS. 7A, B.After exiting from the device 26, the web 20 and the articles 18fastened thereto pass through a cutting or punching device 26 in whichindividual napkins provided with ridge-like elevations are cut-out.

In the described arrangement, the articles 18 are fully symmetrical inshape, such that the front and rear portions of the articles are ofsimilar shape, and glue is applied in the device 19 so that mutuallyfacing ends of the articles 18 will be either rear portions or frontportions of the napkin. As illustrated schematically in FIG. 10, thedevice 25 may include two sets of hinged folding plates 27, 28 that canbe folded to a compressed S-shape and can be moved relative to eachother in the direction of web movement and also relative to the conveyor(not shown) on which the web 20 and its appendant articles aretransported. The devices 25, 26 can move reciprocatingly relative to theline of articles, which are moved with the aid of a conveyor (notshown). In a first position, the folding plates 27, 28 are placedadjacent each other and immediately upstream of the section α′ of thestrip-like web 20 fastened to the backing sheet of the front portion ofan article 18′. The folding plates are then moved in the direction ofmovement R of the articles 18′, 18″ at the same speed as said articles,and the web 20 is folded into an S-shape locally, by folding togetherthe plates 27, 28. When folding of the plates is finished, the plate 28is moved in the upstream direction relative to the plate 27 and givesthe web 20 an S-shape during its upstream movement. The plate 28 ismoved in the upstream direction to a point slightly spaced from thatpart a″ of the section of web 20 fastened to the article 18″. Thearticles 18′, 18″ will now be situated in the device 26, and themutually opposing rear portions of the articles 18′, 18″ are foldedaround the formed string 8″ and fastened thereto. As the rear portionsof the articles 18′, 18″ are folded-in, the devices 25, 26 move in themovement direction R at the same speed as the web 20 and the articles18′, 18″. The devices 25, 26 are then moved back in the upstreamdirection, so as to be positioned correctly for forming strings insubsequent pairs of articles 18 in the process line.

One variant of the described embodiment of a method of manufacturingsanitary napkins in accordance with the invention is shown schematicallyin FIG. 11. This variant differs from the earlier described method byvirtue of applying the strip-like web 29 to the web 30 of napkin blanks31 in a ready-folded shape, said blanks each comprising an absorbentbody enclosed between a top sheet and a backing sheet. The strings 32 ofstrip-like material have thus already been produced when the web 29 ofstrip-like material is placed on the web 30. In the variant shown inFIG. 11, the web 30 is comprised of a coherent line of napkin blanks 31.The web 30 of napkin blanks is produced conventionally, e.g. in aprocess line in accordance with the line described with reference toFIG. 9, although without the short sides of the blanks 31 being cut-outduring passage through the cutting or punching device in said processline. The web of backing material faces towards the viewer in FIG. 11.

Prior to applying the web 29 of strip-like material to the web 30 ofnapkin blanks, the web 30 is provided with a glue string 38 that has awidth corresponding to the greatest width of the web 29 and that extendssymmetrically on respective sides of the longitudinal symmetry line ofthe web 30. When glue is applied, the underside of the web 29, includingthe undersides of the string 32, will adhere to the web 30 of napkinblanks. When the web 29 has fastened to the web 30, the web 30 is foldedaround its longitudinal symmetry line, meaning that the web 30 locatedwithin the regions of the strings 32 will be folded around said stringsand fastened thereto and also to themselves. Individual napkins are thencut from the web, by mutually separating the short sides of mutuallyadjacent napkin blanks. Although not preferred, it is, of course,possible to cut individual napkin blanks from the web 30 prior toapplying the web 29 thereto.

The sanitary napkins produced in this way are suitably packed in theaforesaid folded state, since it is easier to obtain a uniform productstack with the napkins in this form than if the napkins were firstallowed to adopt their three-dimensional shape with an upstanding curvedridge in their rear portions. Naturally, it is also possible toconstruct the device 26 in the way described with reference to FIGS. 9and 10, so that the articles 18, 18′ can be fully folded around theirlongitudinal symmetry axes and packed in a folded-up state.

The napkin blanks illustrated in FIG. 11 include so-called wings which,when the napkin is used, are intended to be folded around the edges ofthe wearer's panties in order to prevent soiling of the garment. Suchwings will, of course, add further security against lateral movement ofa sanitary napkin relative to panties.

The aforedescribed embodiments can, of course, be modified within thescope of the invention, particularly with respect to dimensions of themanufactured napkins. When a sanitary napkin intended for night useshall be produced, it may be appropriate to make the rear portion of thenapkin wider than when a panty protector shall be produced. When thefront and rear portions of the napkins have different shapes, it isnecessary to modify the described processes so that each alternatenapkin in the napkin line will be turned so that the front and rearportions of the napkin lie adjacent to the front and rear portions ofadjacent napkins, or the lengths of the strings of strip material mustalso be adapted to the length of the rear portions of the napkins, i.e.so that each string will extend solely over the rear end of a singlenapkin. The manufacturing arrangement may also include furthercomponents, for instance when the napkin shall include a liquiddispersion layer between the top sheet and the absorbent body. Theinvention is therefore restricted solely by the contents of theaccompanying claims.

1. An absorbent article comprising a front portion, a rear portion, aliquid-permeable top sheet, a liquid-impermeable backing sheet, and anabsorbent body enclosed between the top and backing sheets, wherein therear portion of the article includes a longitudinally extendingridge-shaped elevation that projects out from the side of the articlethat contains the top sheet, wherein a central string of materialextends in the rear portion of the article along the backing sheet onthe side thereof distal from the absorbent body, and the top sheet, thebacking sheet and the absorbent body enclosed therebetween in the rearportion of the article extend around the long sides of said string,wherein those portions of the article which, in the rear portion of saidarticle, extend around the long sides of the string of strip materialabut one another and are fastened to each other in at least one place.2. An absorbent article comprising a front portion, a rear portion, aliquid-permeable top sheet, a liquid-impermeable backing sheet, and anabsorbent body enclosed between the top and backing sheets, wherein therear portion of the article includes a longitudinally extendingridge-shaped elevation that projects out from the side of the articlethat contains the top sheet, wherein a central string of materialextends in the rear portion of the article; the top sheet, the backingsheet and the absorbent body enclosed therebetween in the rear portionof the article extend around the long sides of said string, and whereinthe string comprises a rear portion of a longitudinally extending stripof flexible material that has a high coefficient of friction withrespect to textile material and which extends in the front and the rearportion of the article and is fastened to the backing sheet on the sidethereof that lies distal from the absorbent body.
 3. An absorbentarticle according to claim 2, wherein the strip of flexible material isan elastic foam material.
 4. An absorbent article according to claim 3,wherein the elastic foam material is mounted in the rear portion of thearticle in a stretched state and in the front portion of the article ina relaxed state.
 5. An article according to claim 3, wherein mutuallyadjacent portions of the material in the string of strip material arefastened to each other in at least one place.
 6. An article according toclaim 2, wherein the strip extends symmetrically on both sides of thelongitudinal symmetry axis of the article and has in the front portionof said article a width which is greater than half the smallest width ofthe article in its front portion.
 7. A method of manufacturing anabsorbent article which comprises a front portion and a rear portion andwhich includes a longitudinally extending elevated section in its rearportion, the method comprises; (a) placing a body of absorbent materialon a first sheet of liquid-impermeable material; (b) placing on the bodyof absorbent material a second sheet of liquid-impermeable material, andjoining together the first and second sheets in those parts of thesheets that extend beyond the body of absorbent material, therewithforming a generally flat composite body; (c) placing on the second sheetof the composite body a strip of flexible material that extends over atleast a part of a front and a rear portion of the composite body; (d)fastening the strip to the second sheet in the front portion of thecomposite body; (e) forming that part of the strip which extends in therear portion of the composite body into a longitudinally extendingstring; and (f) folding those parts of the composite body that lie onrespective sides of the longitudinal string of strip material in aroundsaid string and fastening said parts together in at least one place. 8.A method according to claim 7, wherein the strip is comprised of anelastic material, and the part of said strip that extends in the rearportion of the composite body is stretched prior to carrying out step(f).
 9. A method according to claim 7, wherein the longitudinallyextending strip is shaped by folding or rolling the strip together. 10.A method according to claim 7, wherein by fastening the parts of thecomposite body that have been folded-in on respective sides of thelongitudinal string of strip material to said string in at least twolongitudinally spaced sections that extend around the stringcircumference.
 11. A method according to claim 7, wherein forming thatpart of the strip which extends in the rear portions of the compositebody into a longitudinally extending strip prior to placing the strip onthe composite body.